Rav Amrom Gaon, by starting his Teshuva in which he would provide the text for the Tefillot with the rule that a Jew must recite 100 Brachot each day, established that Chazal structured our Tefillot around Brachot. Therefore, understanding the structure of the Brachot leads to a more meaningful Tefila experience.
Three of the rules of Brachot establish which are the key areas of a Bracha. Rule 3:
תלמוד ירושלמי (וילנא) מסכת ברכות פרק א'-כל הברכות אחר חיתומיהן.
Translation: The theme of all the Brachot must be recited in their ending Bracha.
קרבן העדה מסכת תענית פרק ב'-כל הברכה אחר חיתומיהן. עיקר ברכה היא החתימה ומה שמבקש או מתפלל או ברכת הודאה צריך שיהא מוזכר בחתימה:
Translation: All the Brachot follow their concluding words. This means that the main part of a Bracha is the concluding formula; whatever you are requesting or praying for or acknowledging must be referred to in the concluding words of the Bracha.
Rule 4:
תלמוד בבלי מסכת פסחים דף קד' עמ' א'-ואמר רב יהודה אמר שמואל: המבדיל צריך שיאמר מעין חתימה סמוך לחתימתו. ופומבדיתאי אמרי: מעין פתיחתן סמוך לחתימתן.
Translation: And Rab Judah said Samuel's name: He who recites Havdalah must say something in the nature of the conclusion near to its conclusion. While the Pumbeditheans maintain: He must say something about the theme of the Bracha at the commencement of the Bracha just as he does before its conclusion.
Rule 5:
תלמוד בבלי מסכת ברכות דף מ' עמ' ב'-רבי יוסי אומר: כל המשנה ממטבע שטבעו חכמים בברכות - לא יצא ידי חובתו.
Translation: R. Jose says: If one alters the formula laid down by the Sages in Brachot, he has not performed his obligation.
The three rules reveal that every Bracha consists of three key areas: the opening words, the closing formula and the words that precede the closing formula. Here are two examples:
Looking at the structure of these Brachot, we can answer the question: what is the מטבע הברכה that may not be changed? The most important part of a Bracha is its חתימה, the concluding formula. Since its purpose is to state the theme of the Bracha, the words may not be changed. That is why when you compare Nusacha'Ot, you will rarely if ever find differences in the חתימה. Concerning the words that precede the חתימה, we do find variations, which have led to questions being asked. Perhaps the most well-known of these is the Ashkenazic wording just before the Bracha of יוצר המאורות. Rav Sa'Adiya Gaon questioned the wording of אור חדש. He objected to adding words that relate to the light that will shine at the time of the Moshiach in a Bracha that opens and closes with references to the light of the sun, moon and stars. Many Nuscha'Ot agreed with Rav Sa'Adiya's objection. A review of them finds a variation of wording. The Rosh defended the Ashkenazic practice by arguing that the theme of the Bracha is the creation of light during the six days of creation. One form of light that was created at that time was the light that will shine at the time of the Moshiach. Since the world was not worthy of that light, the light was set aside and is being stored until the coming of the Moshiach.
How does knowing these rules lead to engaging in a more meaningful Tefila experience? The rules reveal that special attention should be given to the חתימות הברכות since they disclose the theme of the Brachot. But more importantly, each one is written as words of praise of G-d even in the middle Brachot of Shemona Esrei which represent requests. It is a reminder that one of the important ways that prayer serves as עבודה שבלב, service of the heart, is in our heaping words of praise on the רבונו של עולם.